In "Haven", Lwaxana claimed that Betazoids prided themselves on "complete honesty". Well judging by this episode I guess they don't actually do any such thing.

So the Cairn don't have any concept of spoken language, since they are telepaths with no need for such a thing. So then why did they evolve vocal cords? One can excuse their having mouths, since mouths are also used for eating and breathing. But vocal cords are evolved specifically to allow vocalisation. If the Cairn have never had vocalisation and language, they should never have evolved vocal cords in the first place. I get that they use "vocal enhancers", but the name suggests that those simply improve on their vocalisations - without vocal chords what would there be to enhance at all? Nothing, that's what.

Body Count :

None, unless you count the child who dies in flashback.

Plotline

When Lwuxana Troi starts having a nervous breakdown, Deanna finds out the truth about the sister she never knew.